The present disclosure relates generally to gray ink compositions and methods of making the same.
Gray inks are often used when printing both color and black and white images. When printing inkjet color images, it may be beneficial to form a base using different gray ink tones, and when printing inkjet black and white (grayscale) images, many different gray ink tones may be used to achieve desirable shades.
Generally, gray inks are made by one of two ways. One technique for making gray ink includes diluting black ink. This may, however, result in the hue of the ink shifting. Another technique for making gray ink includes mapping colors (magenta, cyan, and/or yellow) onto the media to obtain the desired hue.
Mapping multiple colored inks may, in some instances, result in a high ink flux on the media that may cause a loss of detail in dark areas. Furthermore, images printed with colored inks to map out neutral and gray areas may be subject to degradation. This may be due, at least in part, to a different lighffastness of each of the individual colors that make up the composite black. Furthermore, when a three-ink system is used, the inks often have a high colorant load in order to achieve adequate chroma, which may result in high grain. Furthermore, it may be difficult to maintain color consistency of neutral grays due, in part, to changing pen drop volumes of the different colors. When two-pen, six-ink (CMYcmk) systems are used, the printed images may, in some instances, take on the hue of the inks in the pen with the higher drop weight. These defects are generally predominant in gray and neutral areas of an image. In some instances, the multi-colorant inks cause the grayscale to be unbalanced, resulting in color-shifted images.
As such, it would be desirable to provide a gray ink that, when printed, is capable of maintaining color consistency and neutrality.